First off I'm a ford dealership mechanic, I used to do it all, "except" go into transmissions.
OK so follow along....on my 2005 corolla LE with the 1zz engine, I usually got around 30-32mpg city driving.
I do very good maintenance on it, i use mobile1 synthetic SINCE 10k miles. with the oil changes done every time the light comes on, using toyota oil filters.
I drain and fill trans with toyota t -type fluid (as indicated on trans dipstick) every 30k miles, and I Drain and fill radiator using toyota red LL coolant every 30k miles also...(its what they gave my the first time i bought coolant from toyota parts, it not the pink stuff).
my tires are michelin tires kept around 40 psi(44 is max rated) rotated about 2 times a year, they have no abnormal wear pattern. So I know its not poor maintenance on the car
So...
I noticed that in 2012 that my fuel milage dropped a few mpg from around 29-31 down to 27-29 mpg.
Then over the summer of 2013 i got 25-27 mpg, then in september of 2013 i got a 24mpg. This all has been a gradual decline in fuel economy, calculated by filling up the tank, resetting the tripometer, driving till the tank is on E, then refilling and dividing the gallons by the miles.
I have around 97000 miles on it now in january 2014.
My check engine light would come on once a year in winter and it was the 02 sensor heater code...it would go away in a few days so i never bothered to change it.
Back around sept of 2013, i was concerned about my milege, so i read on the internet that the intake gaskets get hard and let air past the gasket, so i did toyota intake gasket, and the throttle body gasket, cleaned the throttle body butterfly and i put a denso 02 sensor on it . and put denso iridium spark plugs
Ok now in january of 2014 i'm getting 20 mpg... i noticed on my scan tool my coolant temp is only getting to 185deg. F ,
so i put a Brand new toyota T-stat on it, filled it up with toyota red LL coolant. Rev'd the engine to purge air, topped it off again...pid minitored the coolant temp now getting to 205-206 degs F. then dropped to 194-193, did it again for a few tstat opening cycles, good heat, cooling fan kicked on... parked it around the front called it good. The old Stat looked fine. the new tstat looked a little more robust, but it has the same temp stamp...92C as the old one and looks exactly the same except the springs look a little beefier. 92deg C is 197deg F converted. it should allow the coolant to get to at least 195f
Next day same thing....Its only getting to 185deg F ...i'm like WTF.
So i took my yellow coolant spill proof funnel put it on the radiator filled it up.., to help push air out the the cooling system, and rev'd engine at 3000 rpm and pid monitored the coolant temp...coolant gets to 206-207...tstat opens ,coolant temp drops to 193-194..then it slowly rises again. did it a few opening cycles...seems fine when reving engine high.
Its Still doing it, its only getting to 185deg...Normal driving or ildling , Why is the engine not getting to operating temperature. OR is this normal and i should chase something else?
No codes....runs great.
I haven't changed radiator cap, or the ect sensor...ANY THOUGHTS, what else could it be ?
OK so follow along....on my 2005 corolla LE with the 1zz engine, I usually got around 30-32mpg city driving.
I do very good maintenance on it, i use mobile1 synthetic SINCE 10k miles. with the oil changes done every time the light comes on, using toyota oil filters.
I drain and fill trans with toyota t -type fluid (as indicated on trans dipstick) every 30k miles, and I Drain and fill radiator using toyota red LL coolant every 30k miles also...(its what they gave my the first time i bought coolant from toyota parts, it not the pink stuff).
my tires are michelin tires kept around 40 psi(44 is max rated) rotated about 2 times a year, they have no abnormal wear pattern. So I know its not poor maintenance on the car
So...
I noticed that in 2012 that my fuel milage dropped a few mpg from around 29-31 down to 27-29 mpg.
Then over the summer of 2013 i got 25-27 mpg, then in september of 2013 i got a 24mpg. This all has been a gradual decline in fuel economy, calculated by filling up the tank, resetting the tripometer, driving till the tank is on E, then refilling and dividing the gallons by the miles.
I have around 97000 miles on it now in january 2014.
My check engine light would come on once a year in winter and it was the 02 sensor heater code...it would go away in a few days so i never bothered to change it.
Back around sept of 2013, i was concerned about my milege, so i read on the internet that the intake gaskets get hard and let air past the gasket, so i did toyota intake gasket, and the throttle body gasket, cleaned the throttle body butterfly and i put a denso 02 sensor on it . and put denso iridium spark plugs
Ok now in january of 2014 i'm getting 20 mpg... i noticed on my scan tool my coolant temp is only getting to 185deg. F ,
so i put a Brand new toyota T-stat on it, filled it up with toyota red LL coolant. Rev'd the engine to purge air, topped it off again...pid minitored the coolant temp now getting to 205-206 degs F. then dropped to 194-193, did it again for a few tstat opening cycles, good heat, cooling fan kicked on... parked it around the front called it good. The old Stat looked fine. the new tstat looked a little more robust, but it has the same temp stamp...92C as the old one and looks exactly the same except the springs look a little beefier. 92deg C is 197deg F converted. it should allow the coolant to get to at least 195f
Next day same thing....Its only getting to 185deg F ...i'm like WTF.
So i took my yellow coolant spill proof funnel put it on the radiator filled it up.., to help push air out the the cooling system, and rev'd engine at 3000 rpm and pid monitored the coolant temp...coolant gets to 206-207...tstat opens ,coolant temp drops to 193-194..then it slowly rises again. did it a few opening cycles...seems fine when reving engine high.
Its Still doing it, its only getting to 185deg...Normal driving or ildling , Why is the engine not getting to operating temperature. OR is this normal and i should chase something else?
No codes....runs great.
I haven't changed radiator cap, or the ect sensor...ANY THOUGHTS, what else could it be ?
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